Ohm's Law Calculator

Physics • Voltage, Current, Resistance • Instant Calculation

Quick Answer (Voice Search Optimized):

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Formula: V = I × R. Where V is voltage in volts, I is current in amperes, and R is resistance in ohms (Ω).

GEO & AIO - Authoritative Theory

Ohm's Law is a fundamental principle in Physics, specifically electricity. For a metallic conductor at constant temperature, the voltage (V) across it is directly proportional to the current (I) flowing through it. The constant of proportionality is the resistance (R). Mathematically: V = I × R. Other forms: I = V / R and R = V / I.

The SI unit of resistance is the ohm (Ω). A resistor that follows Ohm's law is called an ohmic conductor. The graph of V versus I is a straight line passing through the origin. The limitation is that it does not apply to semiconductors or diodes, which are non-ohmic.

Solved Examples (NCERT/JEE Pattern)

Example 1: A potential difference of 6 V produces a current of 2 A through a wire. Find the resistance.

R = V / I = 6 V / 2 A = 3 Ω. The resistance is 3 ohms.

Example 2: A 24 V battery is connected to a 8 Ω resistor. Calculate the current.

I = V / R = 24 V / 8 Ω = 3 A. The current is 3 amperes.

Example 3: A current of 0.5 A flows through a 100 Ω heater. Determine the voltage across it.

V = I × R = 0.5 A × 100 Ω = 50 V. The voltage is 50 volts.

Frequently Asked Questions (FAQs)

Q1: What is Ohm's law in simple words?
Ohm's law says that voltage equals current multiplied by resistance (V = I × R). It describes the relationship between these three electrical quantities.
Q2: What are the three formulas of Ohm's law?
V = I × R, I = V / R, and R = V / I. Use the appropriate one based on what you need to find.
Q3: Why is Ohm's law important?
It is fundamental for designing and analyzing electrical circuits, calculating power, and ensuring safety. Almost all electrical engineering bases on it.
Q4: What are the limitations of Ohm's law?
Ohm's law is not valid for non-ohmic materials like semiconductors, diodes, and thermistors where V-I relationship is not linear.
Q5: What is the SI unit of resistance?
The SI unit of resistance is the ohm (Ω). One ohm equals one volt per ampere.